'sar' issue or core dump issue?

From: Lizhang Qin
Date: Tue Mar 02 2010 - 15:07:30 EST


I am experience some performance issue for user space app, when
looking at 'sar' result, it showed things like below.

CPU %user %nice %system %iowait %steal %idle
08:30:02 all 3.29 0.00 9.16 0.01
0.00 87.54
08:30:12 all 0.38 0.00 2.40 0.38
0.00 96.84
08:43:39 all 0.28 0.00 1.17 0.87
0.00 97.68

It shows all the records between 08:30:12 to 08:43:39 are missing.
Does it mean kernel actually lose all the statistic data during that
period? How could that happen though?

I notice there is a big core dump file were written for a crash app
running in the machine.
Could a core dump interfere all the kernel scheduling on all cores (I
have 4 physical CPU adn 8 virtual cores).

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